ESSENTIALS OF DIAGNOSIS
Calcium pyrophosphate deposition (CPPD) disease includes a spectrum of conditions ranging from asymptomatic radiographic changes to severe chronic arthritis.
Acute CPP crystal arthritis, formerly known as pseudogout, shares some clinical features and treatment strategies with acute gout.
The observation of calcium pyrophosphate crystals in synovial fluid is necessary for establishing a definitive diagnosis of CPPD disease.
Chondrocalcinosis on radiograph helps support the diagnosis of CPPD disease.
Premature CPPD disease can be a sign of a hyperparathyroidism, hemochromatosis, hypomagnesemia, or hypophosphatasia as well as familial CPPD disease.
Calcium pyrophosphate deposition (CPPD) disease is a heterogeneous group of arthritic conditions associated with calcium pyrophosphate (CPP) crystals. It is a disease of the elderly, with most patients presenting after the age of 60 years, although familial forms of CPPD and metabolic disorders can cause disease at a younger age. The best known manifestation, acute CPP crystal arthritis, presents with sudden onset of pain and swelling in or surrounding the joint. However, CPPD is a spectrum of conditions ranging from asymptomatic radiographic changes to severe destructive arthritis. Its diverse clinical presentations and ability to mimic other rheumatologic conditions such as gout and rheumatoid arthritis (RA) cause challenges in its diagnosis and treatment. The European League Against Rheumatism (EULAR) has adopted the nomenclature listed in Table 41–1 for the various subtypes of CPPD.
Table 41–1.2011 EULAR nomenclature for classification of subtypes of CPPD. ||Download (.pdf) Table 41–1. 2011 EULAR nomenclature for classification of subtypes of CPPD.
Asymptomatic CPPD disease (found on radiograph without clinical symptoms)
Acute CPP crystal arthritis (pseudogout)
Chronic CPP crystal inflammatory arthritis (pseudo-RA)
OA with CPPD, with or without superimposed acute attacks (pseudo-OA)
Severe joint degeneration (pseudo-neuropathic joint disease)
The true incidence and prevalence of CPPD is unclear, but it is not rare and will likely increase as the population ages. Most prevalence studies are based on radiographs with cartilage calcification (chondrocalcinosis) as evidence of disease. The use of radiographic criteria alone as a disease marker, however, has significant limitations. Up to 20% of patients with proven acute CPP crystal arthritis do not have chondrocalcinosis on imaging. In addition, once joint damage advances in severity, it can be difficult to identify chondrocalcinosis due to cartilage loss. Therefore, the reported rate of 4–7% of the adult population in the United States and Europe likely underreports its true incidence and morbidity. Studies of radiographic findings show that the prevalence of cartilage calcification increases with age. One study demonstrated almost 50% of patients older than 84 years had chondrocalcinosis, compared to 15% of those aged 65–74 years.
Much has been learned regarding the pathogenesis of CPPD disease since calcified cartilage was first described in the early 1900s. ...